Lexmark W820 Service Manual page 151

Step Actions and Questions
3 AC INPUT CHECK
Remove the Rear Cover so you can access the GFI.
Measure the voltage between P/J8-1 and P/J8-3 on the GFI.
Is there approximately 110VAC (or 220VAC if the printer is
the 220VAC model) between P/J8-1 and P/J8-3?
4 AC OUTPUT CHECK
Measure the voltage between P/J7-1 and P/J7-2 on the GFI.
Is there approximately 110VAC (or 220VAC if the printer is
the 220VAC model) between P/J7-1 and P/J7-2?
5 LVPS +5VDC CHECK
Remove the Rear Cover
Measure the voltage between J400-1 and FG, and between
J400-2 and FG on the MCU PWB.
Is there +5VDC between J400-1 and FG, and +5VDC
between J400-2 and FG?
6 LVPS +24VDC CHECK
Measure the voltage between J400-8 and FG on the MCU
PWB.
Is there +24VDC between J400-8 and FG?
7 ESS PWB CHECK
Switch off the Main Switch.
Remove the ESS PWB.
Switch on the Main Switch.
Does the printer go into warm-up?
8 MCU REPLACEMENT
Replace the "Engine Board (MCU PWB)" on page
Does the printer go into warm-up?
9 I/O PWB REPLACEMENT
Replace the "I/O PWB" on page
Does the printer go into warm-up?
4025-XXX
4-92.
4-89.
Yes No
Go to step 4 Replace the
AC power
cord
Go to step 5 Replace the
"Low Voltage
Power
Supply
(LVPS)
Assembly"
on page 4-82
Go to step 6 Go to the
"Printer
Wiring
Diagrams"
on page 5-14
to
troubleshoot a
loss of +5VDC
Go to step 7 Use the Block
Diagrams in
the printer
service
manual to
troubleshoot a
loss of
+24VDC
Replace the Go to step 8
"Controller
Board (ESS
PWB)" on
page 4-94
Problem Go to step 9
solved
Problem Go to step 10
solved
Diagnostic Information
2-55